A consortium of 12 clincial institutions (19 hospitals) located in nine districts of the American College of Obstetricians and Gynecologists in the U.S. provided electronic obstetric, labor and newborn data to create a perinatal database with more than 200,000 deliveries. Selected information were downloaded from the hospital databases and transferred in a de-identified format to the Data Coordinating Center for data auditing, cleaning, recoding and compilation. The de-identified database have been used for secondary data analyses to answer the following questions: What is the currect cesarean delivery practice in the U.S.? How can we reduce the cesarean delivery rate? What is the labor pattern in contemporary population? How to define normal and abnormal labor? When is the best time to perform a cesarean delivery in protracted labor? Answers to these questions may have important clinical implications.